The Washington-based research center reports an estimated 45.3 percent of U.S. households won't owe Uncle Sam — half because they have no taxable income and the other half because they get enough tax breaks to erase their liability, Roberton Williams, a senior fellow at the Tax Policy Center, tells Market Watch.

Market Watch reports taxpayers at the top 1 percent of the income spectrum pay a higher effective income-tax rate than others — around 23 percent, according to Tax Policy Center data from 2014 — and nearly seven times higher than those in the bottom half.

Taxpayers in the bottom 40 percent of the income spectrum wind up getting money back from Uncle Sam.

Tax data also shows:

The richest 20 percent of Americans pay the most in income taxes, shelling out almost 87 percent of all the income tax collected by the government.

The top 1 percent — whose average income is more than $2.1 million — pay 43.6 percent of all federal individual income tax;

The top 0.1 percent — just 115,000 households, whose average income is more than $9.4 million — pay more than 20 percent of all federal individual income tax.